Embodiments of the present disclosure relate to a thin film transistor (TFT) flat sensor and a method for manufacturing the same.
TFT flat X-ray sensors are key elements in digital image technology with advantages such as fast imaging speed, good spatial and density resolution, high ratio of signal-to-noise, direct digital signal output, and are widely applied in medical imaging (such as X-ray chest test), industrial detection (such as metal defect detection), safety detection and air transport.
A traditional array substrate of TFT flat sensors has a structure as illustrated in FIG. 1. The array substrate comprises a plurality of gate scanning lines 10 and a plurality of data scanning lines 11 intersecting each other and a plurality of pixel units defined by the gate scanning lines 10 and the data scanning lines 11. Each pixel unit comprises one field effect transistor (FET) 12 connected with one adjacent gate scanning line 10 and one photodiode 13 connected with the data scanning line 11 via the field effect tube 12 connected to the photodiode 13.
When there is for example X-ray irradiation, the TFT flat sensor senses optoelectronic signals generated by the X-ray through the photodiodes, applies scanning signals to all the pixel units via the gate scanning lines to control On/Off state of the FETs, thereby indirectly controlling data acquisition circuit's reading function for optoelectronic signals generated by all the photodiodes. When an FET is turned on, optoelectronic signals generated by a photodiode corresponding to the FET can be connected to a data scanning line at the output end of the photodiode for acquisition, thus acquisition of photodiode's optoelectronic signals may be implemented by controlling the time sequence of driving signals for gate scanning lines and data scanning lines.
A traditional array substrate of TFT flat sensors has a structure as illustrated in FIG. 2. The X-ray sensor comprises from top to bottom: a substrate 2, a gate electrode 20 on the substrate 2, a gate insulating layer 21 on the gate electrode 20, an active layer 22A and an ohmic contact layer 22B on the gate insulating layer 21, a drain electrode 23A and a source electrode 23B that are on the ohmic contact layer 22B and in the same layer, a data scanning line (not shown) connected with the source electrode 23B, a passivation layer 24 on the drain electrode 23A and the source electrode 23B, a first ITO (indium tin oxide) layer 25A on the passivation layer 24, an insulating layer 26 on the first ITO layer 25A, a second ITO layer 25B on the insulating layer 26, a common electrode 7 on the second ITO layer 25B, a resin buffer layer 28 on the common electrode 27, a resin layer 29 on the resin buffer layer 28, and a third ITO layer 25C on the resin layer 29. The resin buffer layer 28 is used for bonding the bonding resin layer 29.
Traditional TFT flat sensors typically undergo 10 patterning processes during fabrication. Each pattern process generally comprises masking, exposing, developing, etching, stripping and so on. The number of patterning processes can be used as a measurement for simplicity of manufacturing TFT flat sensor. In the manufacturing of TFT flat sensor, the fewer the number of patterning processes is, the shorter the production time is, the higher the production efficiency is, and the lower the manufacturing cost become.